In a long term evolution (LTE) system, wide work bandwidth can be obtained by aggregation of multiple component carriers (CCs) to constitute a downlink and an uplink, i.e., a carrier aggregation (CA) technology, so as to support a high transmission rate. At present, various types of CA are supported, i.e., all aggregated cells are frequency division duplex (FDD) cells, all aggregated cells are time division duplex (TDD) cells TDD uplink configuration and TDD downlink configuration of which are same, all aggregated cells are TDD cells TDD uplink configuration and TDD downlink configuration of which are different, aggregation of FDD cells and TDD cells are also supported. And the TDD uplink configuration and TDD downlink configuration of the TDD cells may be semi-statically configured, or may be dynamically changed.
For a user equipment (UE), when a CA mode is configured, a cell is a primary cell (Pcell), and other cells are referred to as secondary cells (Scells). According to a LTE method, on the Pcell and the Scells, downlink data is transmitted based on a hybrid automatic repeat request (HARQ) mechanism. Accordingly, the UE needs to feed HARQ acknowledgment (HARQ-ACK) corresponding to multiple cells back. For a cell in a FDD system, the HARQ-ACK corresponding to data in a downlink subframe is transmitted in an uplink subframe. For a cell in a TDD system, when the number of downlink subframes is more than the number of uplink subframes in its frame structure, HARQ-ACK corresponding to data in multiple downlink subframes is transmitted in an uplink subframe, wherein the multiple downlink subframes are referred to as a bundling window corresponding to the uplink subframe. For example, a size of the bundling window in a LTE TDD cell may be 1, 2, 3, 4, or 9. According to a LTE method, HARQ-ACK corresponding to all configured cells is fed back in a physical uplink control channel (PUCCH) on the Pcell. In addition, periodic channel state information (P-CSI) of various cells is also mapped to the Pcell for transmission, and aperiodic CSI (A-CSI) of various cells is mapped to a physical uplink shared channel (PUSCH) for transmission.
According to a LTE method, a PUCCH format 3 is supported, and a basic idea of the PUCCH format 3 includes that multiple pieces of uplink control information (UCI) bits, e.g., HARQ-ACK bits, scheduling requests (SRs), and/or P-CSI from multiple configured cells, are jointed encoded, and are mapped to a physical channel for transmission. The PUCCH format 3 may support transmission of at most 22 bits.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.